360 



THE CILIATES 



The rumen ciliates are obligate an- 

 aerobes. The holotrichs (Isolricha and 

 Dasytricha) have been cultivated by Sugden 

 and Oxford (1952), Gutierrez (1955) and 

 others. Diplodinium, Entudinimn , Eudi- 

 plodiniimi, Polyplastron and Metadiniiim 

 have been cultivated by Hungate (1942, 

 1943), Sugden (1953), and others, but 

 Ophryoscolex has not yet been cultivated. 



The holotrichs absorb soluble carbo- 

 hydrates from the medium and convert 

 them into amylopectin, which is stored in 

 ovoid granules measuring 3 by 2)j. and 

 resembling small yeast cells. They are 

 able to utilize glucose, fructose, sucrose, 

 cellobiose, inulin and levans. In addition, 

 both Isotriclia iidestinalia and /. prosloDia 

 rapidly ingest small starch granules and 

 are able to metabolize them. Dasytricha 

 ru))iinantiiu)i does not ingest starch. 

 Gutierrez and Hungate (1957) found that 



D. rimiuiautiii}}} ingested small cocci and 

 occasionally small rod-shaped bacteria; 

 they were able to cultivate this species in 

 a medium containing these types of bac- 

 teria, but not without them. Gutierrez 

 (1958) showed that /so/r/cto prostoma 

 feeds selectively only on certain rods 

 among the many types of rumen bacteria, 

 but that pure strains did not fulfill all the 

 protozoon's growth requirements, since 

 it divided once and then died out in a 

 monobacterial culture. 



The holotrichs produce hydrogen, 

 carbon dioxide, lactic, acetic and butyric 

 acids, and traces of propionic acid (Heald 

 and Oxford, 1953; Gutierrez, 1955). 



Many but not all species of Entodin- 

 iuni ingest and digest starch. According 

 to Kofoid and MacLennan (1930), E. lon- 

 ginuclealuni and E. acutonucleatuni feed 

 selectively on pollen grains. Certain 

 species of Entodi>iium are the predomi- 

 nant starch-ingesters among the rumen 

 protozoa and are the dominant protozoa 

 in animals on full feed. Among those 

 known to ingest starch ar^ E. caudatum , 



E. longinucleatiun, E. ininiDiiuit and £. 

 dubardi. Almost nothing is known about 

 the products of starch fermentation by this 

 genus. Granules of polysaccharide are 

 stored in the outer zone of the endoplasm, 

 but they have never been isolated and 



identified; it would be difficult to separate 

 them from ingested starch granules. 



It has been suggested that carbohy- 

 drate metabolism is dependent upon intra- 

 cellular bacteria. Sugden (1953) was un- 

 able to cultivate E. longinnclealH»i in the 

 presence of streptomycin except when 

 streptomycin-resistant strains of bacteria 

 were present. However, Appleby, Eadie 

 and Oxford (1956), who found various 

 bacteria in disintegrated E)iludinii(in, con- 

 cluded that there was so far no good reason 

 for denying the existence of protozoan en- 

 zyme systems concerned with carbohydrate 

 fermentation. Gutierrez and Davis (1959) 

 found about 100 to 150 gram -positive diplo- 

 cocci (Streptococcus boris) per ciliate in 

 E. caudatum, E. minimum, E. dubardi, 

 E. longinucleatum, E. bursa, E. nanel- 

 lum, E. exiguum and E. vorax in cattle 

 being fed a high starch ration. The cili- 

 ates sometimes ingested starch granules 

 with adherent starch-attacking bacteria. 

 EntodiniuDi species could be cultivated in 

 the presence of S. bovis but not without it. 

 Thus, bacteria are ingested by Entodin- 

 iiiDi and appear to be necessary for its 

 nutrition, but most likely as a source of 

 nitrogen rather than of prefabricated en- 

 zymes. 



Epidinium, like Entodinium, ingests 

 starch and also bacteria; its metabolic 

 products are also unknown. Gutierrez 

 and Davis (1959) found that E. ecaudatum 

 (syn. , DiplodiniuDi ecaudatum ) ingested 

 not only Streptococcus bovis but also other 

 bacteria. 



Diplodinium and related genera 

 (EudiplodiniuDi, Polyplastron, Eremo- 

 plastroii, Metadinium ) ingest and digest 

 cellulose in addition to starch and bacteria. 

 Hungate (1942, 1943) cultured Diplodinium 

 dentatum (syn., D. deniiculatuDt), Poly- 

 plastron multivesiculatum and Eudiplodin- 

 iuni niaggii in media containing dried grass 

 and pure cellulose, but the protozoa failed 

 to grow if the cellulose was omitted. These 

 species and Eremoplastron neglectuni all 

 contained a cellulase. Sugden (1953) found 

 that Metadinium medium also utilized cel- 

 lulose. Gutierrez and Davis (1959) found 

 that E. neglectum and a large unidentified 

 species of ''Diplodinium'' contained gram- 



